271 research outputs found

    A wave-induced stirring mechanism in the mid-depth equatorial ocean

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    A wave-induced stirring and transport mechanism for the mid-depth equatorial ocean is proposed and examined using both analytic linear equatorial wave solutions and a fully nonlinear reduced-gravity model. The study of kinematic stirring using the linear solutions suggests that a superimposition of a few simple equatorial waves can lead to strong Lagrangian stirring and transport along the equator. In particular, a combination of an annual long Rossby wave and a high-frequency Yanai wave appears to be most effective in producing strong stirring in the interior equatorial region. Further investigations of stirring properties using an inverted, fully nonlinear reduced gravity shallow-water model support the results of the kinematic stirring study. By evaluating the finite-time estimates of Lyapunov exponents, we identified two regions where chaotic stirring is most active. One is the western boundary region where short Rossby waves likely play a dominant role in producing the strong chaotic stirring. The other is the equatorial waveguide where a low-frequency Rossby wave prescribes the pattern of the stirring geometry, and a high-frequency Yanai wave plays a role of stirring the fluid. The proposed stirring mechanism provides a plausible explanation of the observed chlorofluorocarbon distribution found in the mid-depth equatorial Atlantic Ocean

    BxDF material acquisition, representation, and rendering for VR and design

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    Photorealistic and physically-based rendering of real-world environments with high fidelity materials is important to a range of applications, including special effects, architectural modelling, cultural heritage, computer games, automotive design, and virtual reality (VR). Our perception of the world depends on lighting and surface material characteristics, which determine how the light is reflected, scattered, and absorbed. In order to reproduce appearance, we must therefore understand all the ways objects interact with light, and the acquisition and representation of materials has thus been an important part of computer graphics from early days. Nevertheless, no material model nor acquisition setup is without limitations in terms of the variety of materials represented, and different approaches vary widely in terms of compatibility and ease of use. In this course, we describe the state of the art in material appearance acquisition and modelling, ranging from mathematical BSDFs to data-driven capture and representation of anisotropic materials, and volumetric/thread models for patterned fabrics. We further address the problem of material appearance constancy across different rendering platforms. We present two case studies in architectural and interior design. The first study demonstrates Yulio, a new platform for the creation, delivery, and visualization of acquired material models and reverse engineered cloth models in immersive VR experiences. The second study shows an end-to-end process of capture and data-driven BSDF representation using the physically-based Radiance system for lighting simulation and rendering

    Mapping midwifery and obstetric units in England

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    OBJECTIVE: to describe the configuration of midwifery units, both alongside&free-standing, and obstetric units in England. DESIGN: national survey amongst Heads of Midwifery in English Maternity Services SETTING: National Health Service (NHS) in England PARTICIPANTS: English Maternity Services Measurements descriptive statistics of Alongside Midwifery Units and Free-standing Midwifery Units and Obstetric Units and their annual births/year in English Maternity Services FINDINGS: alongside midwifery units have nearly doubled since 2010 (n = 53-97); free-standing midwifery units have increased slightly (n = 58-61). There has been a significant reduction in maternity services without either an alongside or free-standing midwifery unit (75-32). The percentage of all births in midwifery units has trebled, now representing 14% of all births in England. This masks significant differences in percentage of all births in midwifery units between different maternity services with a spread of 4% to 31%. KEY CONCLUSIONS: In some areas of England, women have no access to a local midwifery unit, despite the National Institute for Health&Clinical Excellence (NICE) recommending them as an important place of birth option for low risk women. The numbers of midwifery units have increased significantly in England since 2010 but this growth is almost exclusively in alongside midwifery units. The percentage of women giving birth in midwifery units varies significantly between maternity services suggesting that many midwifery units are underutilised. IMPLICATIONS FOR PRACTICE: Both the availability and utilisation of midwifery units in England could be improved

    Icebergs in the North Atlantic: Modelling circulation changes and glacio-marine deposition

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    In order to investigate meltwater events in the North Atlantic, a simple iceberg generation, drift, and melting routine was implemented in a high-resolution OGCM. Starting from the modelled last glacial state, every 25th day cylindrical model icebergs 300 meters high were released at 32 specific points along the coasts. Icebergs launched at the Barents Shelf margin spread a light meltwater lid over the Norwegian and Greenland Seas, shutting down the deep convection and the anti-clockwise circulation in this area. Due to the constraining ocean circulation, the icebergs produce a tongue of relatively cold and fresh water extending eastward from Hudson Strait that must develop at this location, regardless of iceberg origin. From the total amount of freshwater inferred by the icebergs, the thickness of the deposited IRD could be calculated in dependance of iceberg sediment concentration. In this way, typical extent and thickness of Heinrich layers could be reproduced, running the model for 250 years of steady state with constant iceberg meltwater inflow

    Diagnosing the energy cascade in a model of the North Atlantic

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    Spectral potential and kinetic energy densities and fluxes in horizontal wavenumber space are estimated in an eddy-resolving model of the North Atlantic. In agreement to recent observational results near surface kinetic energy fluxes are negative over wide regions of the North Atlantic, indicative of an inverse energy cascade. This inverse kinetic energy cascade is found over a wide depth range but both the spectral kinetic energy density and the corresponding flux show no clear dependency on Rossby radius or Rhines scale. Potential energy fluxes tend to be positive and show a direct potential energy cascade towards a scale which is related to the Rossby radius in the subtropical North Atlantic

    Adrenergic gene polymorphisms and cardiovascular risk in the NHLBI-sponsored Women's Ischemia Syndrome Evaluation

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    <p>Abstract</p> <p>Background</p> <p>Adrenergic gene polymorphisms are associated with cardiovascular and metabolic phenotypes. We investigated the influence of adrenergic gene polymorphisms on cardiovascular risk in women with suspected myocardial ischemia.</p> <p>Methods</p> <p>We genotyped 628 women referred for coronary angiography for eight polymorphisms in the α<sub>1A</sub>-, β<sub>1</sub>-, β<sub>2</sub>- and β<sub>3</sub>-adrenergic receptors (<it>ADRA1A</it>, <it>ADRB1, ADRB2</it>, <it>ADRB3</it>, respectively), and their signaling proteins, G-protein β 3 subunit (<it>GNB3</it>) and G-protein α subunit (<it>GNAS</it>). We compared the incidence of death, myocardial infarction, stroke, or heart failure between genotype groups in all women and women without obstructive coronary stenoses.</p> <p>Results</p> <p>After a median of 5.8 years of follow-up, 115 women had an event. Patients with the <it>ADRB1 </it>Gly389 polymorphism were at higher risk for the composite outcome due to higher rates of myocardial infarction (adjusted hazard ratio [HR] 3.63, 95% confidence interval [95%CI] 1.17–11.28; Gly/Gly vs. Arg/Arg HR 4.14, 95%CI 0.88–19.6). The risk associated with <it>ADRB1 </it>Gly389 was limited to those without obstructive CAD (n = 400, P<sub>interaction </sub>= 0.03), albeit marginally significant in this subset (HR 1.71, 95%CI 0.91–3.19). Additionally, women without obstructive CAD carrying the <it>ADRB3 </it>Arg64 variant were at higher risk for the composite endpoint (HR 2.10, 95%CI 1.05–4.24) due to subtle increases in risk for all of the individual endpoints. No genetic associations were present in women with obstructive CAD.</p> <p>Conclusion</p> <p>In this exploratory analysis, common coding polymorphisms in the β<sub>1</sub>- and β<sub>3</sub>-adrenergic receptors increased cardiovascular risk in women referred for diagnostic angiography, and could improve risk assessment, particularly for women without evidence of obstructive CAD.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT00000554.</p

    Campylobacter jejuni bacteremia and Helicobacter pylori in a patient with X-linked agammaglobulinemia

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    We describe a 15-year-old patient with X-linked agammaglobulinemia who developed malabsorption and bacteremia due to infection of Helicobacter pylori and Campylobacter jejuni. The Campylobacter bacteremia was only recognized after subculturing of blood culture bottles that failed to signal in the automated system. After 2 weeks of treatment with meropenem and erythromycin for 4 weeks, the patient developed a relapse of bacteremia 10 months later with a high level erythromycin resistant C. jejuni. Sequencing revealed an A2058C mutation in the 23 S rRNA gene associated with this resistance. Treatment with doxycycline for 4 weeks finally resulted in complete eradication. This case report illustrates the importance for physicians to use adapted culture methods and adequate prolonged therapy in patients with an immunodeficiency. A summary of published case reports and series of patients with hypogammaglobulinemia or agammaglobulinemia with Campylobacter or Helicobacter bacteremia is given
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